Heath Ledger mourned from Hollywood to Australia

Hollywood stars Mel Gibson, John Travolta and Nicole Kidman on Wednesday joined the Australian prime minister to pay tribute to Heath Ledger -- the boy from Perth who rose to become a screen heartthrob.

Ledger, who skyrocketed to global fame with his Oscar-nominated role as a gay cowboy in Ang Lee's "Brokeback Mountain", was found dead in his New York apartment on Tuesday. He was 28.

Gibson, who plucked Ledger from relative obscurity to play his son in 2001's US war of independence epic "The Patriot", said the death of the versatile actor was a "tragic loss."

"I had such great hope for him," the Oscar-winning actor and director said.

"He was just taking off and to lose his life at such a young age is a tragic loss. My thoughts and prayers are with him and his family."

Australian screen star Nicole Kidman called Ledger's death a "tragedy" and said her heart went out to his family, while John Travolta described him as "one of my favorite actors."

"His abilities are rare... it's a tremendous loss," Travolta said.

Ledger had recently completed filming on Warner Bros' upcoming summer blockbuster "The Dark Knight," in which he played Batman's arch-foe the Joker.